1. Field of the Invention
This invention relates to a support pole and a means for attaching a traffic signal support arm thereto. Further, the invention relates to a means for strengthening the connection of the support arm to the pole as well as strengthening the connection of the pole to a base plate which is mounted on a concrete footing.
2. Description of the Related Art
In many cases, it is desirable or necessary to position a traffic signal light over a roadway. In some cases, the traffic signal is supported by cables strung between a pair of poles which are located on opposite sides of the roadway. In other instances, an upstanding pole is positioned at one side of the roadway and has a traffic signal support arm secured thereto which extends outwardly therefrom over the roadway with the traffic signal being supported thereon. In some cases, the inner end of the support arm is welded to a flat mounting plate with that mounting plate being bolted to a flat support plate which is either welded to the pole or which is clamped onto the pole. In some cases, the support plate on the pole is vertically disposed and in other situations the support plate is slightly inclined with respect to the vertical. Further, in some cases, the inner end of the support arm is shaped or coped to conform to the outer surface of an arcuate support plate which is clamped onto the pole with the support arm being welded to the outer surface of the arcuate support plate.
In those structures wherein a flat support plate is mounted on the pole, the most common method of attaching the support arm to the pole is to weld the mounting plate to the inner end of the support arm by inserting the inner end of the support arm into a circular opening formed in the mounting plate with the outer surface of the support arm being welded to the mounting plate completely around the circumference of the support arm. In some cases, the arm is attached to the plate using a partial or full penetrating groove butt weld. Inasmuch as the support arm is normally a tapered tube of thin wall construction, separation of the support arm from the mounting plate sometimes occurs at the location where the support arm is welded to the mounting plate. Separation occurs because the wall of the support arm cracks adjacent to the outside weld due to fatigue stress induced by cyclic loading created by wind gusts, vibration due to vortex shedding or galloping, or air movement caused by vehicular traffic.
The lower end of the support pole for the traffic signal support arm normally has a flat base plate welded thereto with the base plate being secured to a suitable concrete footing or the like by means of anchor bolts. The support pole is welded to the base plate in generally the same fashion as the support arm is welded to its mounting plate. The prior art support poles have experienced some cracking in the area immediately above the base plate in the pole wall adjacent to the weld. In some cases, the lower end of the support pole is received within a circular opening formed in the base plate. In other cases, the lower end of the support pole is butt welded to the upper surface of the base plate using a partial or full penetration groove weld.
An improved support pole having a traffic signal support arm attached thereto is described. In particular, a means is described which strengthens the connection between the support pole and its supporting base plate and a means is also provided for strengthening the connection between the support arm and the pole. A horizontally disposed base plate is provided which is adapted to be attached to a footing. The base plate has a circular opening formed therein which receives the lower end of the pole member with the lower end of the pole member being welded to the base plate within the circular opening. In some cases, the lower end of the support pole is butt welded to the upper surface of a flat base plate. A first strengthening ring, having upper and lower ends, embraces the pole member above the base plate. The upper end of the first strengthening ring is welded to the exterior surface of the pole member. The lower end of the first strengthening ring is welded to the exterior surface of the pole member above the base plate and is welded to the upper surface of the base plate.
A support plate is secured to the pole member at one side there above the lower end thereof. A mounting plate is secured to the support plate and has a circular opening formed therein which receives the inner end of an elongated support arm. The inner end of the support arm is welded to the mounting plate within the circular opening formed therein. In some cases, the inner end of the support arm is butt welded to the outer surface of the mounting plate. A second strengthening ring embraces the support arm outwardly of the mounting plate and has an inner end and an outer end. The outer end of the second strengthening ring is welded to the exterior surface of the support arm. The inner end of the second strengthening ring is welded to the mounting plate and to the exterior surface of the support arm. All of the welds described above are continuous weldments. The use of the second strengthening ring between the inner end of the support arm and the mounting plate strengthens the connection between the support arm and the mounting plate to prevent separation thereof. The use of the first strengthening ring between the lower end of the pole and the base plate strengthens the connection between the pole member and the base plate to prevent separation thereof.
It is a principal object of the invention to provide an improved means for attaching a traffic signal support arm to a pole.
A further object of the invention is to provide an improved means for attaching the lower end of a support pole to a base plate.
Still another object of the invention is to provide an improved means for attaching a roadway light support arm, a sign support arm or a camera support arm to a support pole.
Still another object of the invention is to provide a means for attaching a traffic signal support arm to a mounting plate at the inner end thereof through the use of a strengthening ring which embraces the inner end of the support arm and which is welded to the support arm and to the mounting plate.
These and other objects will be apparent to those skilled in the art.